Repeatability Of Retinal Oximetry Using Ultra-high Resolution Optical Coherence Tomography

Abstract

 

Purpose:

 

Retinal oxygen saturation provides important information about the metabolic state of the retina. Many ocular diseases, such as diabetic retinopathy, glaucom, and retinal vein occlusion, have changes of retinal blood flow and oxygen saturation. The purpose of this study was to investigate the feasibility and repeatability of retinal oximetry using slit-lamp adapted ultra-high resolution optical coherence tomography (SL-UHR-OCT).

 

Methods:

 

SL-UHR-OCT was developed with an advanced optical delivery system adapted into a slit-lamp for retinal imaging. The system has a ~3µm depth resolution. Fringe patterns for spectral analysis were obtained from the central retinal artery and vein. A-scans at central wavelengths of 805 and 855 nm were analyzed for calculating optical density ratios (ODRs), representing oxygen saturation in the retinal vessels. Both eyes of twenty healthy subjects (15 women and 5 men, age 37.7 ± 9.4 years) were imaged 2 different sessions on the same day. Coefficients of repeatability (CRs) were calculated. Bland-Altman plot of the difference between the two measurements was used to evaluate consistency.

 

Results:

 

Mean retinal arterial ODR were 0.75 (SD 0.61) and 0.72 (SD 0.69) in sessions 1 and 2, respectively. ODR’s mean (SD) values of the vein were 0.13 (0.63) and 0.14 (0.74) between two sessions, which were significantly lower than arterial ODR (P < 0.05). The CRs between the two sessions were 1.55 and 1.70 for the artery and vein respectively. The range of inter-sessions correlation coefficient (ICC) was 0.23-0.35 (Figure 1).

 

Conclusions:

 

We demonstrated the feasibility and documented the repeatability of using OCT oximetry for evaluating retinal oxygen saturation. The extended function of measuring oxygen saturation may expand OCT usage for ophthalmic research. Further studies of large sample of healthy and diseased eyes are needed to assess and optimize measured variations.  

 

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • oxygen • retina